1. Field of the Invention
The present disclosure relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a method of fabricating the same.
2. Discussion of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). Presently, many efforts and studies are being made to develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these flat panel displays, LCD devices have many advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements.
In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmissivity of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a perspective view illustrating an LCD device according to the related art.
Referring to FIG. 1, the LCD device includes an array substrate 10, a color filter substrate 20 and a liquid crystal layer 30 between the array substrate 10 and the color filter substrate 20.
The array substrate 10 includes gate and data lines 14 and 16 crossing each other on a first substrate 12 to define a pixel region P. A thin film transistor Tr is formed at a crossing portion of the gate and data lines 14 and 16. A pixel electrode 18 in the pixel region P is connected to the thin film transistor Tr.
The color filter substrate 20 includes a black matrix 25 on a second substrate 22 and corresponding to the gate and data lines 14 and 16 and the thin film transistor Tr. A color filter layer 26 corresponds to the pixel region P. The color filter layer includes red (R), green (G) and blue (B) color filter patterns 26a, 26b and 26c corresponding to the respective pixel regions P. A common electrode 28 is formed on the black matrix 25 and the color filter layer 26.
Although not shown in the drawings, a sealant is formed along peripheral portions of the array substrate 10 and the color filter substrate 20 to attach the array substrate 10 and the color filter substrate 20. Alignment layers to align liquid crystal molecules of the liquid crystal layer 30 are formed at the array substrate 10 and the color filter substrates, respectively. Polarizing plates are formed on outer surfaces of the array substrate 10 and the color filter substrate 20, respectively. A backlight unit is below the array substrate 10 to supply light.
When a gate signal is supplied to the gate line 14, the thin film transistor Tr is turned on and a data signal is supplied through the data line 16 to the pixel electrode 18. Accordingly, an electric field is induced between the pixel electrode 16 and the common electrode 28, and images are displayed through the LCD device.
Recently, the LCD device is employed in various electronic devices such as a television (TV), a projector, a mobile station, a person digital assistant (PDA) and the like, and these devices performs specific operations through user's touch on a display screen.
To realize the touch function, it is required that the LCD device further includes additional elements such as touch blocks sensing touch and sensing lines connected to the touch blocks. The sensing lines of low resistance metal are formed at a layer different from the layers where the gate and data lines are formed. Since the sensing lines should transfer information of position, where touch sensed by a touch sensor occurs, to x and y sensing circuits, which are located at a non-display region of the LCD device, the sensing lines in x and y directions are formed. In this case, since the sensing lines in the x and y directions are all formed at the same layer, the x sensing line in the x direction and the y sensing line in the y direction would necessarily cross and be short-circuited therebetween. This short-circuit between the x sensing line and the y sensing line should be prevented. Particularly, the short-circuit, in the touch block, between the x sensing line and the y sensing line should be prevented. To do this, an auxiliary line is used as a detour path for the x sensing line. In other words, the auxiliary line is formed at the same layer and of the same material as the gate line and is connected to the x sensing line, and the short-circuit between the x and y sensing lines is thus prevented.
The touch block senses little change of capacitance that occurs when a user touches a display screen using a user's finger, converts the change of capacitance into a signal such as a current, and transfers the signal to the x and y sensing circuits through the respective sensing lines. Accordingly, minute currents flow on the sensing lines. For the currents to reach the x and y sensing circuits through the sensing lines, the sensing lines should have low resistance per unit area.
The auxiliary line used as a portion of the sensing line should also have low resistance, and to do this, the auxiliary line should increase in width or thickness. However, in the case of the width increase of the auxiliary line, reduction of aperture ratio of the LCD device is caused. Further, in the case of the thickness increase of the auxiliary line, thickness increase of the gate line, which is formed at the same process of forming the auxiliary line, is caused, and, in an etching process to form the auxiliary line and the gate line, difference of etching ratio between a center portion and a peripheral portion of the array substrate occurs and thus non-uniformity of gate line pattern is caused.